[Sidefx-houdini-list] particle birth - deforming source

Larry Giunta larry at gcreativestudios.com
Wed Aug 23 12:35:11 EDT 2006

Kind of an interesting problem.

We're working on a close up, side shot
of the surface of bubbling soda.

We're trying to control one particle
system so the bubbles birth,
hangout/float on the surface ( which is an
animated deforming/rippling grid) then rise
up and out of frame.

We can get all the timing of events
correct by grouping particles based
on $LIFE, etc. before forces are applied.

The tough part is having the particles float
on the surface after they are born.
When they birth from the animating surface,
they stay where they are born ( don't
float on the surface).

A promising fix for this was to birth
particles from a flat grid then creep
the whole system on the deforming
surface back in SOPs. However, once
the particles rise up off the surface they appear to be flipping
all over the place because they are still essentially
being crept on the rippling surface.
This was a nice, fast solution but may
need to be abandoned because we
can't seem to control the erratic motion
when they rise above the surface.

Is there a way to birth particles from a rippling/deforming
surface but have the particles stay stuck to that
surface until a certain point in life ( when forces can
make it float off).

Been playing with the collision POP, but the interaction
is slow and not so predictable. Wondering if there
is an easier way. Will continue to search but thought
it might be worth posting this one.


Larry Giunta
Creative Director
G Creative Studios
larry at gcreativestudios.com

More information about the Sidefx-houdini-list mailing list